1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * PIKA FPGA based Watchdog Timer
4 *
5 * Copyright (c) 2008 PIKA Technologies
6 * Sean MacLennan <smaclennan@pikatech.com>
7 */
8
9 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
10
11 #include <linux/init.h>
12 #include <linux/errno.h>
13 #include <linux/module.h>
14 #include <linux/moduleparam.h>
15 #include <linux/types.h>
16 #include <linux/kernel.h>
17 #include <linux/fs.h>
18 #include <linux/miscdevice.h>
19 #include <linux/watchdog.h>
20 #include <linux/reboot.h>
21 #include <linux/jiffies.h>
22 #include <linux/timer.h>
23 #include <linux/bitops.h>
24 #include <linux/uaccess.h>
25 #include <linux/io.h>
26 #include <linux/of.h>
27 #include <linux/of_address.h>
28
29 #define DRV_NAME "PIKA-WDT"
30
31 /* Hardware timeout in seconds */
32 #define WDT_HW_TIMEOUT 2
33
34 /* Timer heartbeat (500ms) */
35 #define WDT_TIMEOUT (HZ/2)
36
37 /* User land timeout */
38 #define WDT_HEARTBEAT 15
39 static int heartbeat = WDT_HEARTBEAT;
40 module_param(heartbeat, int, 0);
41 MODULE_PARM_DESC(heartbeat, "Watchdog heartbeats in seconds. "
42 "(default = " __MODULE_STRING(WDT_HEARTBEAT) ")");
43
44 static bool nowayout = WATCHDOG_NOWAYOUT;
45 module_param(nowayout, bool, 0);
46 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
47 "(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
48
49 static struct {
50 void __iomem *fpga;
51 unsigned long next_heartbeat; /* the next_heartbeat for the timer */
52 unsigned long open;
53 char expect_close;
54 int bootstatus;
55 struct timer_list timer; /* The timer that pings the watchdog */
56 } pikawdt_private;
57
58 static struct watchdog_info ident __ro_after_init = {
59 .identity = DRV_NAME,
60 .options = WDIOF_CARDRESET |
61 WDIOF_SETTIMEOUT |
62 WDIOF_KEEPALIVEPING |
63 WDIOF_MAGICCLOSE,
64 };
65
66 /*
67 * Reload the watchdog timer. (ie, pat the watchdog)
68 */
pikawdt_reset(void)69 static inline void pikawdt_reset(void)
70 {
71 /* -- FPGA: Reset Control Register (32bit R/W) (Offset: 0x14) --
72 * Bit 7, WTCHDG_EN: When set to 1, the watchdog timer is enabled.
73 * Once enabled, it cannot be disabled. The watchdog can be
74 * kicked by performing any write access to the reset
75 * control register (this register).
76 * Bit 8-11, WTCHDG_TIMEOUT_SEC: Sets the watchdog timeout value in
77 * seconds. Valid ranges are 1 to 15 seconds. The value can
78 * be modified dynamically.
79 */
80 unsigned reset = in_be32(pikawdt_private.fpga + 0x14);
81 /* enable with max timeout - 15 seconds */
82 reset |= (1 << 7) + (WDT_HW_TIMEOUT << 8);
83 out_be32(pikawdt_private.fpga + 0x14, reset);
84 }
85
86 /*
87 * Timer tick
88 */
pikawdt_ping(struct timer_list * unused)89 static void pikawdt_ping(struct timer_list *unused)
90 {
91 if (time_before(jiffies, pikawdt_private.next_heartbeat) ||
92 (!nowayout && !pikawdt_private.open)) {
93 pikawdt_reset();
94 mod_timer(&pikawdt_private.timer, jiffies + WDT_TIMEOUT);
95 } else
96 pr_crit("I will reset your machine !\n");
97 }
98
99
pikawdt_keepalive(void)100 static void pikawdt_keepalive(void)
101 {
102 pikawdt_private.next_heartbeat = jiffies + heartbeat * HZ;
103 }
104
pikawdt_start(void)105 static void pikawdt_start(void)
106 {
107 pikawdt_keepalive();
108 mod_timer(&pikawdt_private.timer, jiffies + WDT_TIMEOUT);
109 }
110
111 /*
112 * Watchdog device is opened, and watchdog starts running.
113 */
pikawdt_open(struct inode * inode,struct file * file)114 static int pikawdt_open(struct inode *inode, struct file *file)
115 {
116 /* /dev/watchdog can only be opened once */
117 if (test_and_set_bit(0, &pikawdt_private.open))
118 return -EBUSY;
119
120 pikawdt_start();
121
122 return stream_open(inode, file);
123 }
124
125 /*
126 * Close the watchdog device.
127 */
pikawdt_release(struct inode * inode,struct file * file)128 static int pikawdt_release(struct inode *inode, struct file *file)
129 {
130 /* stop internal ping */
131 if (!pikawdt_private.expect_close)
132 del_timer(&pikawdt_private.timer);
133
134 clear_bit(0, &pikawdt_private.open);
135 pikawdt_private.expect_close = 0;
136 return 0;
137 }
138
139 /*
140 * Pat the watchdog whenever device is written to.
141 */
pikawdt_write(struct file * file,const char __user * data,size_t len,loff_t * ppos)142 static ssize_t pikawdt_write(struct file *file, const char __user *data,
143 size_t len, loff_t *ppos)
144 {
145 if (!len)
146 return 0;
147
148 /* Scan for magic character */
149 if (!nowayout) {
150 size_t i;
151
152 pikawdt_private.expect_close = 0;
153
154 for (i = 0; i < len; i++) {
155 char c;
156 if (get_user(c, data + i))
157 return -EFAULT;
158 if (c == 'V') {
159 pikawdt_private.expect_close = 42;
160 break;
161 }
162 }
163 }
164
165 pikawdt_keepalive();
166
167 return len;
168 }
169
170 /*
171 * Handle commands from user-space.
172 */
pikawdt_ioctl(struct file * file,unsigned int cmd,unsigned long arg)173 static long pikawdt_ioctl(struct file *file,
174 unsigned int cmd, unsigned long arg)
175 {
176 void __user *argp = (void __user *)arg;
177 int __user *p = argp;
178 int new_value;
179
180 switch (cmd) {
181 case WDIOC_GETSUPPORT:
182 return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
183
184 case WDIOC_GETSTATUS:
185 return put_user(0, p);
186
187 case WDIOC_GETBOOTSTATUS:
188 return put_user(pikawdt_private.bootstatus, p);
189
190 case WDIOC_KEEPALIVE:
191 pikawdt_keepalive();
192 return 0;
193
194 case WDIOC_SETTIMEOUT:
195 if (get_user(new_value, p))
196 return -EFAULT;
197
198 heartbeat = new_value;
199 pikawdt_keepalive();
200
201 return put_user(new_value, p); /* return current value */
202
203 case WDIOC_GETTIMEOUT:
204 return put_user(heartbeat, p);
205 }
206 return -ENOTTY;
207 }
208
209
210 static const struct file_operations pikawdt_fops = {
211 .owner = THIS_MODULE,
212 .llseek = no_llseek,
213 .open = pikawdt_open,
214 .release = pikawdt_release,
215 .write = pikawdt_write,
216 .unlocked_ioctl = pikawdt_ioctl,
217 .compat_ioctl = compat_ptr_ioctl,
218 };
219
220 static struct miscdevice pikawdt_miscdev = {
221 .minor = WATCHDOG_MINOR,
222 .name = "watchdog",
223 .fops = &pikawdt_fops,
224 };
225
pikawdt_init(void)226 static int __init pikawdt_init(void)
227 {
228 struct device_node *np;
229 void __iomem *fpga;
230 u32 post1;
231 int ret;
232
233 np = of_find_compatible_node(NULL, NULL, "pika,fpga");
234 if (np == NULL) {
235 pr_err("Unable to find fpga\n");
236 return -ENOENT;
237 }
238
239 pikawdt_private.fpga = of_iomap(np, 0);
240 of_node_put(np);
241 if (pikawdt_private.fpga == NULL) {
242 pr_err("Unable to map fpga\n");
243 return -ENOMEM;
244 }
245
246 ident.firmware_version = in_be32(pikawdt_private.fpga + 0x1c) & 0xffff;
247
248 /* POST information is in the sd area. */
249 np = of_find_compatible_node(NULL, NULL, "pika,fpga-sd");
250 if (np == NULL) {
251 pr_err("Unable to find fpga-sd\n");
252 ret = -ENOENT;
253 goto out;
254 }
255
256 fpga = of_iomap(np, 0);
257 of_node_put(np);
258 if (fpga == NULL) {
259 pr_err("Unable to map fpga-sd\n");
260 ret = -ENOMEM;
261 goto out;
262 }
263
264 /* -- FPGA: POST Test Results Register 1 (32bit R/W) (Offset: 0x4040) --
265 * Bit 31, WDOG: Set to 1 when the last reset was caused by a watchdog
266 * timeout.
267 */
268 post1 = in_be32(fpga + 0x40);
269 if (post1 & 0x80000000)
270 pikawdt_private.bootstatus = WDIOF_CARDRESET;
271
272 iounmap(fpga);
273
274 timer_setup(&pikawdt_private.timer, pikawdt_ping, 0);
275
276 ret = misc_register(&pikawdt_miscdev);
277 if (ret) {
278 pr_err("Unable to register miscdev\n");
279 goto out;
280 }
281
282 pr_info("initialized. heartbeat=%d sec (nowayout=%d)\n",
283 heartbeat, nowayout);
284 return 0;
285
286 out:
287 iounmap(pikawdt_private.fpga);
288 return ret;
289 }
290
pikawdt_exit(void)291 static void __exit pikawdt_exit(void)
292 {
293 misc_deregister(&pikawdt_miscdev);
294
295 iounmap(pikawdt_private.fpga);
296 }
297
298 module_init(pikawdt_init);
299 module_exit(pikawdt_exit);
300
301 MODULE_AUTHOR("Sean MacLennan <smaclennan@pikatech.com>");
302 MODULE_DESCRIPTION("PIKA FPGA based Watchdog Timer");
303 MODULE_LICENSE("GPL");
304
